DAO 86:205-212 (2009)  -  DOI: https://doi.org/10.3354/dao02127

Identifying potential virulence determinants in viral haemorrhagic septicaemia virus (VHSV) for rainbow trout

S. Campbell1,2,*, B. Collet2, K. Einer-Jensen3, C. J. Secombes1, M. Snow2

1Scottish Fish Immunology Research Centre, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK
2Marine Scotland, Marine Laboratory, PO Box 101, 375 Victoria Road, Aberdeen AB11 9DB, UK
3National Veterinary Institute, Technical University of Denmark, Hangøvej 2, 8200 Århus N, Denmark

ABSTRACT: We identified viral haemorrhagic septicaemia virus (VHSV) isolates classified within Genotype Ib which are genetically similar (>99.4% glycoprotein amino acid identity) yet, based on their isolation history, were suspected to differ in virulence in juvenile rainbow trout. The virulence of an isolate recovered in 2000 from a viral haemorrhagic septicaemia disease episode in a marine rainbow trout farm in Sweden (SE-SVA-1033) was evaluated in juvenile rainbow trout via intraperitoneal injection and immersion challenge alongside 3 isolates recovered from wild-caught marine fish (DK-4p37, DK-5e59 and UKMLA98/6HE1) suspected of being of low pathogenicity to trout. Mortality data revealed that isolate SE-SVA-1033 caused VHSV-specific mortality in both intraperitoneal and immersion challenges (75.0 and 15.4%, respectively). The remaining Genotype Ib isolates caused significantly lower mortalities using the same experimental infection routes (<35.0 and <2.0%, respectively). Having identified VHSV isolates with clear differences in their pathogenicity, coding and inter-genic non-coding regions of 2 isolates (SE-SVA-1033 and DK-4p37) were determined and compared in order to identify potential markers responsible for the observed differences in virulence. Only 4 predicted amino acid substitutions were identified across the genome sequenced; these occurred in the N (R46G), G (S113G), NV (L12F) and L (S56A) proteins. These findings form the basis for further studies aimed at determining the biological significance of these mutations and suggest that small changes at the molecular level can cause significant changes in the virulence properties of VHSV isolates.


KEY WORDS: Rainbow trout · VHSV · Pathogenicity · Sequencing · Virulence determinants


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Cite this article as: Campbell S, Collet B, Einer-Jensen K, Secombes CJ, Snow M (2009) Identifying potential virulence determinants in viral haemorrhagic septicaemia virus (VHSV) for rainbow trout. Dis Aquat Org 86:205-212. https://doi.org/10.3354/dao02127

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